• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.4
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• pp.377-385
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• 2007

Drivers passing through a tunnel fare some difficulties caused by the visual differences between outside and inside of the tunnel. The blackhole phenomenon at a tunnel entrance lone severely decreases the driver's visibility during the daytime. A counterbeam lighting is generally recommended for the prevention of it. This paper simulates an entrance zone with a blackhole phenomenon to verify the effect of counterbeam lighting. Even though the tunnel lighting is important, It Is not easy to consider many lighting alternatives at the stage of tunnel design due to the complexity of tunnel renditions. This paper is expected to contribute improving the visibility in tunnels, especially at the entrance zone.

• Journal of IKEEE
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• v.20 no.1
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• pp.31-44
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• 2016

This paper presents a hole-filling algorithm based on extrapolating spatial-temporal background information used in view synthesis for free-viewpoint television. A new background codebook is constructed and updated in order to extract reliable temporal background information. In addition, an estimation of spatial local background values is conducted to discriminate an adaptive boundary between the background region and the foreground region as well as to update the information about the hole region. The holes then are filled by combining the spatial background information and the temporal background information. In addition, an exemplar-based inpainting technique is used to fill the rest of holes, in which a priority function using background-depth information is defined to determine the order in which the holes are filled. The experimental results demonstrated that the proposed algorithm outperformed the other comparative methods about average 0.3-0.6 dB, and that it synthesized satisfactory views regardless of video characteristics and type of hole region.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6A
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• pp.853-859
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• 2008

As a new system of steel pipe pile cap reinforcement, the application of perforated flat bar bolted to the steel pipe pile head was suggested for the improvement of structural performance of footing structure. This study investigates the structural characteristics of perforated flat bar shear connectors according to shape and diameter of hole, number of rebars passing through the hole and the depth of settlement. The result shows several requirements to ensure sufficient pull-out resistance and ductility such as that the hole diameter excluding diameter of rebar should exceed the size of aggregates; the hole should be perforated with diameter as the half of plate height; and the adequate depth of settlement should be ensured for the optimal performance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.4
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• pp.98-106
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• 2008

The strengthening in terms of efficiency, easy, economics is very popular method when it is applied to a damaged structures. The purpose of this study develops anchorage system that supports enough strengthening effect without any damage. In addition it is checked whether the method can be conveniently applied to structures. To verify strengthening effect a flexural experiments were performed. Four concrete beams were constructed and tested. Deflections, strains and modes of failure were recorded to examine strengthen of beams. Comparing crack load of each experimental data, yielding load, ultimate load, ductility index, and tendon stress were analyzed.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.125-128
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• 2008

In the recent construction industry, external tendon method has been widely used for strengthening and repair of civil structures. This paper presents the strengthening effectiveness and application of the proposed external tendons using lifting hole anchorage system. Based on the experimental results of the previous external tendons using lifting hole anchorage systems, two types of modified systems were proposed. In order to verify the strengthening effectiveness of the two systems, six beams were built and a series of experiments was carried out. To compare and analyze the behaviors of the proposed systems, deflections and strains were measured. Additionally, yield load, ultimate load and failure modes were compared and analyzed.

• Journal of Power System Engineering
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• v.11 no.2
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• pp.72-76
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• 2007

Since the magnetic bearing system has unstability inherently it is necessary to measure the displacement for stable operation. Normally the displacement measurement is implemented by using sensors. The sensor for the displacement measurement is selected by precision, installation space, effect of magnetic field and response speed. And the cost of displacement measurement sensor also is considered. At the cost the hall effect sensor has a large advantage comparing with the others. Therefore this study concern about the basis experimental test for the displacement measurement of the magnetic bearing system that uses the hall effect sensor coupled with a tiny permanent magnet. The experimental results confirm the validity and practicability for this displacement measurement sensor.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.8
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• pp.1266-1272
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• 2003

This paper presents a new class of magnetic microsensors based on the Hall effect in AC microplasma. In the theoretical study, we develop a simple model of the plasma Hall sensor and express the plasma Hall voltage as a function of magnetic field, plasma discharge field, pressure, and electrode geometry. On this basis, we have designed and fabricated magnetic microsensors using AC neon plasma. In the experiment, we have measured the Hall voltage output of the plasma microsensors for varying five different conditions, including the frequency and the magnitude of magnetic field, the frequency and the magnitude of plasma discharge voltage, and the neon pressure. The fabricated magnetic microsensors show a magnetic field sensitivity of 8.87${\pm}$0.18㎷/G with 4.48% nonlinearity.

• Proceedings of the Korean Magnestics Society Conference
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• 1997.11a
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• pp.38-39
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• 1997

• Proceedings of the Korean Magnestics Society Conference
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• 2000.05a
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• pp.118-119
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• 2000

• Explosives and Blasting
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• v.41 no.4
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• pp.41-50
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• 2023

This study, a vertical double-deck method using an electronic detonator was applied to increase excavation volume and reduce blast pollution. In the double deck method, there is a possibility that blasting efficiency may be reduced if bottom deck blasting is carried out without the free surface being completely formed after upper deck blasting. And for this reason, the blasting efficiency of the double deck method varies depending on the deck delay time. Therefore, in this study, we proposed four deck delay times applying 1 to 5 times the hole delay time. And blasting efficiency was evaluated according to fragmentation analysis. As a result of the fragmentation evaluation, the fragmentation of pattern 4 (deck delay time = hole delay time×5) was the best, but it was confirmed that fragmentation efficiency increased significantly from pattern 3 (deck delay time = hole delay time×3). Accordingly, it is analyzed that when blasting a vertical double deck, the deck delay time must be at least three times the hole delay time to obtain an efficient blasting effect.